How was federalism implemented and regarded in the early years of the union?
I'm taking it you mean federalism the theory animating the Federalist Party, rather than federalism, as in the Federalist Papers, meaning advocacy on behalf of the ratification of the Constitution?
Assuming that's right, this is a very broad question that basically calls for a narrative of the entirety of American political history, from 1789 to at least Andrew Jackson! If that's what you're after, there's actually a book on just that subject: What Hath God Wrought, by Howe. I've been meaning to pick it up for a while now but I hear good things.
Rather than narrate the rise and fall of the Federalist Party, I might focus you on one issue that defined its existence: the national bank. During Washington's presidency, the Cabinet extensively debated whether Congress could (and if so whether it should) create a national bank capable of running the nation's finances and paying down its war debt. Jefferson and his allies, the future Democratic-Republican Party, opposed this, out of both an inherent distrust of banks and financial elites, and a doubt that Congress could lawfully charter a banking corporation. The former is evident in Jefferson's correspondence; the latter in the early Supreme Court case McCullough v. Maryland, where that very question was litigated. But now we're getting ahead of ourselves.
The origin of the bank was at least as much practical as ideological. Alexander Hamilton, an early cabinet minister, war hero, and financial luminary, argued for the bank as the only way to set the government's finances on sound footing. Much of Washington's cabinet was against the proposal, and Washington tapped Hamilton to make the case for it. The result was an extensive exposition of the limits of Congressional power under the "necessary and proper clause," an interpretation that the Supreme Court would alter adopt, generally, in McCullough. Washington concurred with Hamilton's assessment, and when the bill chartering the bank landed on his desk, he signed it. The bank would go on to be a success in some respects and a failure in others, and continue to animate debates between Federalists, who were for it and an expansive reading of state power, and Democratic-Republicans, who were not.
This is a broad sketch. I encourage you to consult any of these sources: